Turning your life around?

I'm now 18, but when I was 15 I got into a relationship with a really bad guy. He got me heavily into drugs, and his style of life. Before I knew it I was paying for his crack, and watched while he made out with other girls. When I was 17, I finally had the courage to break up with him, and now he is in jail. I now I'm suffering the aftermath. I failed a year of school, and everyone knows me as a , and as a druggie, but I'm really trying to change. I don't even think that anyone gives me a chance. What should I do?